Bolt spline



Jan. 1, 1957 P. H. DIXON ET AL BOLT SPLINE 4 Sheets-Sheet l P11111 H- Dixon Muyrmrd E.Wm11in Filed May l, 1950 Jan. l, 1957 P. H. DIXON ET AL 4 Sheets-Sheet Filed May l, 1950 Pun] H DiXDI-L Muynuvd B Wnllin LLf/ Jan. 1, 1957 P. H. DIXON ET Az.

BOLT SPLINE 4 Sheets-Sheet Filed May l, 1950 Pt'xul H- Ihxnn Maynard BWnlliI-L Jan. l, 1957 P. H. DlxoN ET AL 2,775,920

BOLT SPLINE Filed May l, 1950 4 Sheets-Sheet 4 P11111 H. D iX un Mnynnrd El. Wnllin BOLT SPLINE Paul H. Dixon and Maynard B. WallinyRockfordg Ill., as-

signors to the United States ofAmerica as represented bythe Secretary of the. Army Application May 1, 1950; SerialiNo.v159,33'6f 4 Claims.. (Cl. 89--188) This invention relates to automatic aircraft-cannon and more particularly to'shuttle-type boltmechanism for said cannon.

An object of the invention is a gas operatedbolt'mechanism that results in a reduction of'th'e overalllengthof the cannon.

Another object of the invention-isashuttle type, gas operated bolt that will remainpositivel-yv locked luntil the peakv gas-pressure in the chamber has diminished.

Another object of the inventionv isV a shuttlel type bolt utilizingthe gases of theredround for unlocking the J bolt.

Another object of the invention is a shuttle type bolt where the body of the bolt is held against rotation and the head of the bolt is rotated to lock and unlockthe bolt during counterrecoil and recoil.

Another object of the'invention-is aV shuttle type bolt mechanism which prevents unlocking ofl the bolt until the gas pressure in the gun tube; has dropped to av safe value and which permits use of the residual gas pressure in the tube after unlockingjthe boltV to" additionally accelerate the bolt.

The speciiic nature of'the inventionas well .as-other objects and;advantagesthereofI will clearly appear from the following description anddrawingslin which:

Figure 1 is alongitudinal sectional view of thercannon, particularly showing the-bolt; butter andlocking'nicchia'- IllSl'Il;

Figure 2 is a longitudinal sectionalviewshowing the bolt insection and its cooperatinglockingmeans in the breech ring.

Figure 3 is an enlarged longitudinalv section showing the bolt in locked position.

Figure'4 is an enlarged horizontal section takenV along line iL-4' of Figure 6; showingthebolt'in lockedposition,` and the bolt` pistons; g

Figure S isa section taken alonglineS-S' o-Fi'gure' l.

Figure 6 is a sectiontaken along line` 6"-6ot` Figure: l.

Figure 7 is a section' taken through the bolt alongline 7--7 in Figure 2.

Figure 8` is an elevational'viewof' the bo'ltjV assembly withthe boltV head in section showingthe helical'` splines of the boltbody.

Figure 9V isa sectional View of' the bolt head showing the helical splinesl on the interior of the beltl head;

Figure l() is a' diagram showingthe relationship ofthe bolt head` to the stop'ring, and tlie relationship of' helical splines when thebolt members arev iir extended position.

' Figure l1 isA a diagramsimilar to that shownin Figure l0, but'with'the bolthead rotated".

Figure l2 is a diagranr similar to thatl shown in Figure l0, but withV thehead'rotated` 30y andiflly locked in the breech inserts.

Figure 13 is a front view of the `bolt'v head.v

Figure 14 is an explodedV viewshowing the breech inserts and bolt stopV ringin perspective;

assembled to thebreech ring,

nited States Patent Referring more particularly to the drawings, there is shown in Figure l a gun barrel l having a chamber 2, and provided with a breech ring 3 iixed to the' barrel as at 4. The breech ring has formed in its surface' a rack 5' which upon recoil winds the spring motor of the feed mechanism` 6 through the` pinions 7. The feed mechanism o is contained in the housing 8 which is releasably ixed in the' top ofthe receiver 9. Assembled in the rearmost part of the receiver is a bolt butter assembly ltl This buffer is not designed to dissipate theV energy of the recoiling bolt as the name implies, but is designed toreturn as much-of theenergy as possible to the shuttle bolt 45. The bolt buier is a simple unit of six leaf springsy 10a. The buffer assembly is secured intov place by the receiver end` cap 9a, which screws on the end of the receiver and is held againstunloosening'by'a conventionalv spring loaded lock, not shown; The six springs are assembled in pairs of two each. Each pair is meshed together under load by formed endsV on one spring in each pair. The pair of rear leaf springs are thicker and therefore have a stiffer spring scale. This is to keep the variable amount of bolt travel within closer limits. The six springs are confined in a package comprising mainlyV two identical guides 11, only one of which is shown, arranged so that the springs will stay in proper alignment during the b-ung stroke. These guides also serve to hold theV bolt body lgagainstrotation, when the bolt assembly extends beyond the horizontal slide rail assemblies 12 and i3- during the buiimg stroke. The piston supporting arms 2G and 21 are received'by tracks 12al and 13a, formed in the guides, during this buffer compression and thereby prevent rotation of the bolt body. Horizontal slide rail assemblies 12 and 13 extending from the butter assembly to a point intermediate the length of the receiver are fastened to the receiver wallsby means of machine screws' trib and are provided with a T-shaped groove Z'b and 13b respectively. Slidably received in the grooves-12b' and 13b are H-shaped telescoping rails 14 and 15 having their ends 14a and 15a lixed in the breech rings slotted lugs lo and 1/ re spectively. The shuttle bolt comprises a non-rotating body 1S and a rotating bolt head 19. The rear of the bolt body is formed with diametrically opposed piston supporting arms 20 and 21 and two diametrically opposed arms 22 and 23, angularly spaced from the piston supporting arms. As best shown in Figure 5v the piston supporting arm' 20 and arms 22 slidably embrace the rails lZland 14, and the piston supporting arm 21 and arm 23 likewise embrace the rails 13 and l5l during recoil and counterrecoil movement ofthe bolt and prevents rotation of the bolt body. Positioned Within the breech ring adjacent the' chamber end of the gun' barrel is'a stop ring 24 having cams 25 and 26 in slots 27 and 28y for cooperationrwith cams 29 andt and cams 31' and 32 extending radially ofi the bolt head face 33- to convert the longitudinal momentum ofthe bolt head'into rotational energy, see Figures l0, l1 and l2 and` 14. The'stop ring is held against rotatory motion'fbymeans of a tongue 34 fitted inslot 35 formed in the'breecli ring. The-stop' ring is also slotted diametrically'opposite the tongue to receive the forward end of the extractor 42 mountedon' the bolt head, as` shown in Figure 5. Two breech ring inserts136 and 37 are provided with internal interrupted threads 38 and 39 respectively, for locking engagement with thev interrupted threads ttlV formed on the `outside of the bolthead. The breech ring inserts abut the stop sure area of gun tube are bled through passages 48 in the gun tubes and 49 in the breech ring, and likewise through passages 50 and 51 to act against the pistons 46 and 47 to start unlocking of the bolt. Reference characters 52 and 53 indicate restrictions in the gas passages 49 and 50 for controlling the pressure against the pistons. Reference numerals 54 and 55 indicate the obturating bushings in gas passages 48 and 50 respectively. The bolt body 18 comprises a cylindrical portion 56 having formed thereon at its forward end three groups of helical splines 57, 58 and 59. Splines 57 and 58 are spaced from each other by means of an annular groove 60, and splines 58 and 59 spaced from each other by means of an annular groove 61, which interrupt the teeth as shown in Figure 8. The teeth of the rear most splines 57 are but one half the thickness of the teeth of splines 58 and 59. The rear end of the cylindrical portion 56 has integral therewith a cross member generally indicated by 62 having formed therein the piston supporting arms 20 and 21 and the `arms 22 and 23 hereinbefore described. The top side of the cross member is grooved as at 63 to accommodate the extractor. The bolt body is longitudinally bored, as indicated by reference numeral 64. The forward end of the bore being reduced in diameter and forming an annular ange 65. A bolt head sleeve 66 having one end fixed in the longitudinal bore 67 projects into the bore 64 and has its opposite end provided with a ange 68. A helical spring 69 mounted on the sleeve 66 is conned between the flanges 68 and 65 and thrusts against the bolt head sleeve to retain the bolt in locked position. The sleeve is secured by a step out 70 in the sleeve support bushing 71 which has a central perforation 72 providing a passage for the lelectric firing pin 73. The firing pin is centrally supported in the rear portion of the body by means of an insulation disk 74 and longitudinally by a sleeve of insulation 75 reciprocal in the bolt head sleeve 66. An insulated lead 76 in the cross member connects the electric firing pin with a contact member 77 mounted on one of the piston bearing arms as best shown in Figure 5. The electric ring pin is spring loaded to assure contact with primers of varying depth by means of a spring 78 xed in the bore 64 and bearing against the insulation disk 74 which supports the head of the tiring pin. Figure 9 shows three groups of helical splines 79, 80 and 8l formed in the wall of the longitudinal bore 67 of the bolt head. The splines 79 and 80 are separated by groove 82 and splines 80 and 81 are separated by groove 83 for coaction with the splines and grooves formed on the bolt body. Fixed in the rearmost part ot the bolt head bore 67 adjacent the splines 79 is a spline stop ring 84 held in position by a snap ring in groove 86.

It will be assumed that the bolt is in the battery or closed position. When a round is tired the gases are bled from the chamber through passages in the gun barrel and breech ring to the pist-on chambers and applied to the pistons which exert a force upon the bolt body, which is longitudinally slidable on the slider rails and which is held against rotational movement by the arms formed in the cross member of the bolt body and embracing the slider rails, and starts to unlock the bolt. This causes a lengthwise displacement between the bolt body and bolt head and the spline connections between the bolt body and head act to rotate the head and disengage the cams on the bolt head and stop ring and the interrupted threads on the bolt head and breech ring inserts. At the completion of the displacement the ends of the rear spline 57 on the bolt body bear against the spline stop ring; the bolt head has rotated 24 degrees and the splines 58 and 59 on the bolt body are in line with the annular grooves 82 and 83 on the bolt head, see Figure 11. The bolt head momentum completes the last 6 degrees of rotation. In this 6 degrees, the splines 58 and 59 intermesh with the annular grooves 82 and 83 and the splines 81, 59, 80 and 59 are in alignment with each other thereby locking the bolt in its extended position. The helical spring located inside the bolt and thrusting against the bolt head sleeve, retains the bolt in this extension. The rear splines 57 on the bolt body and 79 on the bolt head remain in engagement, see Figure l0. However, the teeth on the rear spline of the bolt body are thinned to one half the normal tooth thickness. This allows for the 6 degrees of bolt head rotation without tooth interference with the rear splines. In the meantime the bolt completes its recoil motion by engaging the butter which bounces the bolt into counterrecoil motion which is arrested when the bolt head collides with the bolt head stop ring to start the bolt locking motion. The energy required for locking during automatic re is provided by the kinetic energy in the bolt assembly. This is applied by means of the helical spline connection between the bolt body and bolt head. The bolts longitudinal momentum is converted into rotational energy by inclined surfaces on the cams in the bolt stop ring. In doing so the bolt 4head rst collides with the bolt stop ring and the cam slopes 31a and 32a on the bolt head engage the cam slopes 25a and 26a on the bolt stop ring. This imparts initial rotation to the bolt head; and causes the bolt head to rotate 6 degrees; thereby unmeshing the splines 5S and 59 with the annular grooves 82 and 83 and positions the splines of the head and body for engagement with each other. The forward momentum of the bolt body then causes the helical splines to rotate the bolt head 24 degrees to complete locking. The interrupted threads or the bolt head and on the breech ring insert are now completely meshed. The bolt head rotation is brought to a stop, at the completion of locking, by the cam slopes 29a and 30a on the bolt head, colliding with the cam slopes 26h and 25b on the bolt stop ring as indicated in Figure l2. This eliminates undesirable stress on the splines.

We claim:

l. In an automatic cannon, a bolt mechanism comprising a two piece bolt slidably mounted on rails positioned in the receiver of said cannon, a breech ring having a portion extending rearwardly of the breech, a bolt stop ring in said breech ring adjacent said breech and restrained against longitudinal movement therein by means of inserts in said breech ring, the inserts being provided with interrupted threads on their inner surfaces for locking engagement with mating threads on said bolt, the wall of said stop ring provided with diametrically opposed slots, each of said slots having a cam formed in the base thereof and extending inwardly of said wall, said bolt comprising a longitudinally bored cylindrical body having arms formed on the rear end of said body, said arms embracing the rails to prevent rotation of said body, groups of helical splines on the periphery of said body, said bolt head comprising a cylindrical body having groups of splines formed in a longitudinal bore thereof and in engagement with said body splines, diametrically opposite pairs of cams on the forward end of said head member, the cams of each of said pairs angularly spaced to straddle one of said cams on said stop ring, interrupted threads on said head member adjacent to and in alignment with the cams formed on said head member, one cam of each pair of cams upon collision of said head member and stop ring engages a cam on said stop ring to initially impart rotation to said head member and align the interrupted teeth of said head and inserts, said body continuing in counterrecoil to further rotate said head and mesh said teeth, said one cam of each pair of cams disengaging its respective stop ring cam, the other of each pair engaging said respective cam to limit the rotation of said head.

2. The invention as set forth in claim l wherein the splines on said body are circumferentially disposed and longitudinally spaced by annular grooves forming three groups of splines, the rearmost group of splines being approximately twice as long and 'one half the thickness of the other groups, said head splines comprising three groups longitudinally spaced along the bore of said head to form intermediate annular grooves, the intermediate grooves of said head splines receiving in alignment with said head splines the said other groups of body splines when said bolt is in extended position, said rearmost body splines contacted by one group of the head splines during recoil to limit the rotation of said head and align the head and body splines, said body and head splines moving out of alignment upon collision of said head and stop ring during counterrecoil movement of the bolt, said body continuing in counterrecoil movement to cause spline action to rotate and lock said head, and means to maintain said bolt in extended position.

3. The invention as set forth in claim 2 wherein said means comprises a sleeve having a substantially closed front anged end mounted in the face of said head, the body of said sleeve extending in the longitudinal bores of said head and body, a rear flange formed on t-he opposite end of the sleeve in sliding contact with the wall of said bolt body bore, the bolt body bore terminating at its forward end in an inwardly directed flange, a spring mounted on said sleeve between said rear ange and bolt body ilange, said spring maintaining said bolt in extended position and said splines in alignment during recoil and counterrecoil movement of the bolt.

4. In an automatic cannon, a bolt mechanism comprising a two piece bolt comprising a head portion and a body portion slidably mounted in said cannon, a breech ring having a portion extending rearwardly of the breech, a bolt stop ring in said breech ring adjacent said breech and restrained against longitudinal movement therein by means of inserts in said breech ring, said inserts being provided with interrupted threads on their inner surfaces for locking engagement with mating threads on said bolt, the wall of said stop ring provided with diametrically opposed slots, each of said slots having a cam formed in the base thereof and extending inwardly of said wall, helical splines formed on the periphery of said body portion, said bolt head having helical splines formed in a longitudinal bore thereof and in engagement with said body splines, diametrically `opposed pairs of cams on said head member and spaced to straddle one of said cams on the said stop ring, one cam of each pair of cams upon collision of said head member and said stop ring engaging a stop ring cam to initially impart rotation to said head member, the said helical body splines circumferentially disposed and longitudinal* ly spaced by annular grooves forming three groups of splines, the rearmost group being substantially twice as long and one-half the thickness of the other groups, the said head splines comprising three groups longitudinally spaced along the bore of said head to form intermediate annular grooves, the intermediate grooves of said head splines receiving in alignment the said other groups of body splines when said bolt is in extended position, the said rearmost body splines engaged by one group of said head splines during recoil motion to limit the rotation of said head and align the head and body splines, said body and head splines moving out of alignment upon collision of said head and stop ring during counterrecoil motion of said bolt, said body continuing in counterrecoil movement to cause spline action to rotate said head.

References Cited in the tile of this patent UNITED STATES PATENTS 516,768 Teibert Mar. 20, 1894 601,177 Stockett Mar. 22, 1898 729,413 Reifgraber May 26, 1903 804,986 Stamm Nov. 21, 1905 991,962 Eastwick May 9,. 1911 1,020,849 Smith et a1 Mar. 19, 1912 1,291,689 Sheppard Jan. 14, 1919 1,637,233 Norman July 26, 1927 2,494,889 Maillard Ian. 17, 1950 2,501,069 Maillard Mar. 21, 1950 FOREIGN PATENTS 151,781 Germany June 17, 1904 160,666 Austria Oct. 10, 1941 718,111 Germany Mar. 3, 1942 719,180 Germany Apr. 1, 1942 438,061 Italy July 23, 1948 438,064 Italy July 23, 1948 261,414 Switzerland Aug. 16, 1949 

